Display device

ABSTRACT

A display device uses a control unit to analyze an image obtained by picturing a user using an image-capturing unit and detect a line of sight of the user with respect to the display region of a display unit. Further, the control unit identifies observation condition information indicating the condition of the user viewing the display region based on the detected line of sight of the user. A display control unit writes the image signal in the display region of the display unit for each frame, wherein the display control unit halts, for a predetermined frame period, writing of the image signal in a controlled region when the identified observation condition information meets a predetermined requirement, the controlled region being at least a part of the display region.

TECHNICAL FIELD

The present invention relates to a display device and, moreparticularly, to a technique for controlling display depending on thecondition of a user viewing the display screen.

BACKGROUND ART

JP Hei09(1997)-120323 A discloses a technique for reducing powerconsumption according to the use condition of the electronic device.According to JP Hei09(1997)-120323 A, a line of sight of a user isdetected from an image obtained by picturing the user using theelectronic device and the tilt of the electronic device is detected, andthe power supply of the electronic device is controlled depending on thedetected parameters. More specifically, according to JPHei09(1997)-120323 A, if the line of sight of the user is not in thedirection of the electronic device and the electronic device has beentilted by a certain amount or more for a certain period of time orlonger, power supply to the display control unit of the electronicdevice is stopped and the backlight is turned off. That is, according toJP Hei09(1997)-120323 A, an image is displayed when the user is viewingthe display screen, and no image is displayed when the user is notviewing the display screen.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

When the user sometimes glances at the screen of the display device,controlling display according to JP Hei09(1997)-120323 A causes thescreen to be switched between display states too often such that thescreen may flicker or the time between switches between the displayconditions of the screen may vary significantly. That is, merelyswitching display on the screen depending on whether the user is viewingthe screen may not enable controlling display in a fine manner dependingon the condition of the user viewing the screen, meaning low visibilityor convenience.

An object of the present invention is to provide a technique forcontrolling display in a manner suitable for the condition of the userviewing the screen without decreasing visibility or convenience.

Means to Solve the Problems

A display device according to a first invention includes: a display unithaving a display region in which an image signal is written; a detectionunit configured to analyze an image obtained by picturing a user anddetect a line of sight of the user with respect to the display region;an identification unit configured to identify observation conditioninformation indicating a condition of the user viewing the displayregion based on the line of sight detected by the detection unit; and adisplay control unit configured to write the image signal in the displayregion for each frame, wherein the display control unit halts, for apredetermined frame period, writing of the image signal in a controlledregion when the observation condition information identified by theidentification unit meets a predetermined requirement, the controlledregion being at least a part of the display region.

According to a second invention, starting from the first invention, thedisplay control unit changes a length of the predetermined frame perioddepending on the observation condition information.

According to a third invention, starting from the first or secondinvention, the controlled region is a static image region of the displayregion in which a static image contained in an image represented by theimage signal is displayed.

According to a fourth invention, starting from one of the first to thirdinventions, the observation condition information includes at least oneof a number of times the line of sight of the user directed to thedisplay region moves per unit time and a time for which the user viewsthe display region within a unit time, and the predetermined requirementis the observation condition information having a value equal to orsmaller than a predetermined threshold.

According to a fifth invention, starting from one of the first to thirdinventions, the identification unit further identifies a predeterminedobserved range including an observed position within the display regionto which the line of sight of the user is directed, the observationcondition information includes at least one of a number of times theline of sight of the user directed to the display region moves per unittime and a time for which the user views the display region within aunit time, the controlled region is a portion of the display region thatis other than the predetermined observed range, and the predeterminedrequirement is the observation condition information having a valueequal to or smaller than a predetermined threshold.

Starting from the fourth or fifth invention, a sixth invention furtherincludes: a backlight configured to illuminate the display unit withlight; and a backlight control unit configured to reduce a luminance ofthe backlight when the observation condition information has a valuethat is equal to or smaller than the predetermined threshold.

According to a seventh invention, starting from the first invention, theobservation condition information includes an observed position in thedisplay region to which the line of sight of the user is directed, andthe predetermined requirement is a movement of the observed positionwithin the display region matching a predetermined movement pattern.

According to an eighth invention, starting from one of the first toseventh inventions, the display unit includes an active-matrixsubstrate, the active-matrix substrate including: gate lines and sourcelines disposed to cross the gate lines; pixel electrodes each providedfor a pixel defined by one of the gate lines and one of the sourcelines; and thin-film transistors each having a semiconductor layerprovided above one of the gate lines, a gate terminal connected withthat gate line, a source terminal connected with one of the sourcelines, and a drain terminal connected with one of the pixel electrodes,the source terminal and the drain terminal being located above thesemiconductor layer and spaced apart from each other.

According to a ninth invention, starting from the eight invention, thesemiconductor layer contains an oxide semiconductor.

According to a tenth invention, starting from the ninth invention, theoxide semiconductor contains indium, gallium, zinc and oxygen.

According to an eleventh invention, starting from the tenth invention,the oxide semiconductor is crystalline.

The arrangement of the present invention enables controlling display ina manner suitable for the condition of the user viewing the screenwithout decreasing visibility or convenience

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a display device in a firstembodiment.

FIG. 2 is a schematic view of the display panel of FIG. 1.

FIG. 3 is a schematic view of the active-matrix substrate of FIG. 2 andvarious components for driving the active-matrix substrate.

FIG. 4A is an equivalent circuit of one pixel.

FIG. 4B is a schematic cross-sectional view of the pixel of FIG. 4A.

FIG. 5 illustrates the correspondence between the observation conditioninformation and display control pattern in the first embodiment.

FIG. 6 is a timing chart illustrating how data signals are written whenthe normal control in the first embodiment is performed.

FIG. 7A is a timing chart illustrating how data signals are written whenthe display control for Pattern A of FIG. 5 is performed.

FIG. 7B is a schematic view of an example static image region on theactive-matrix substrate.

FIG. 8 is a timing chart illustrating how data signals are written whenthe display control for Pattern B of FIG. 5 is performed.

FIG. 9 is a timing chart illustrating how data signals are written whenthe display control for Pattern C of FIG. 5 is performed.

FIG. 10 illustrates the correspondence between the observation conditioninformation and display control pattern in a second embodiment.

FIG. 11A is a schematic view of an example predetermined range on theactive-matrix substrate for Pattern E of FIG. 10.

FIG. 11B is a timing chart illustrating how data signals are writtenwhen the display control for Pattern E of FIG. 10 is performed.

FIG. 12 schematically illustrates how the line of sight of the usermoves in Variation (3).

EMBODIMENTS FOR CARRYING OUT THE INVENTION

A display device in an embodiment of the present invention includes: adisplay unit having a display region in which an image signal iswritten; a detection unit configured to analyze an image obtained bypicturing a user and detect a line of sight of the user with respect tothe display region; an identification unit configured to identifyobservation condition information indicating a condition of the userviewing the display region based on the line of sight detected by thedetection unit; and a display control unit configured to write the imagesignal in the display region for each frame, wherein the display controlunit halts, for a predetermined frame period, writing of the imagesignal in a controlled region when the observation condition informationidentified by the identification unit meets a predetermined requirement,the controlled region being at least a part of the display region (firstarrangement).

In the first arrangement, the detection unit detects a line of sight ofthe user with respect to the display region from an image obtained bypicturing the user, and the identification unit identifies observationcondition information about the user with respect to the display regionbased on the detected line of sight. The display control unit writes animage represented by image signals in the display region for each frame,and halts, for a predetermined frame period, writing of image signals ina controlled region when the observation condition information about theuser meets a predetermined requirement, the controlled region being atleast a part of the display region. Writing of image signals in at leastpart of the display region is halted for a predetermined frame perioddepending on the condition of the user viewing the display region, butimages are displayed on the display region. Thus, the decrease in thevisibility of images or convenience will be smaller than inimplementations where images are displayed only when the viewer isviewing the screen. Further, halting for a predetermined frame periodwriting of image signals in at least a part of the display region willreduce power consumption encountered when images are displayed.

In a second arrangement, starting from the first arrangement, thedisplay control unit may change a length of the predetermined frameperiod depending on the observation condition information.

In the second arrangement, the predetermined frame period can be changeddepending on the observation condition information about the user. Thiswill enable controlling display in a manner that is more suitable forthe condition of the user viewing the display region compared withimplementations where the predetermined frame period is constant,thereby further reducing power consumption encountered when images aredisplayed.

In a third arrangement, starting from the first or second arrangement,the controlled region may be a static image region of the display regionin which a static image contained in an image represented by the imagesignal is displayed.

In the third arrangement, writing of image signals in a still imageregion may be halted for a predetermined frame period. Still imagescontain less movement than moving images, and thus visibility is lesslikely to decrease even when writing of image signals in a still imageregion is halted for a predetermined frame period. Further, since animage is also displayed in the still image region such that powerconsumption will be reduced without making the user noticing somethingodd.

In a fourth arrangement, starting from one of the first to thirdarrangements, the observation condition information may include at leastone of a number of times the line of sight of the user directed to thedisplay region moves per unit time and a time for which the user viewsthe display region within a unit time, and the predetermined requirementmay be the observation condition information having a value equal to orsmaller than a predetermined threshold.

In the fourth arrangement, the condition of the user viewing the displayregion may be identified based on at least one of the number of timesthe line of sight directed to the display region moves per unit time andthe time for which the line of sight is directed to the display regionwithin a unit time. Further, when the observation condition informationhas a value that is equal to or smaller than a predetermined threshold,writing of image signals in the controlled region is halted for apredetermined frame period. This will enable controlling display in amanner more suitable for the condition of the user than inimplementations where writing of image signals is halted depending onwhether the user views the display region.

In a fifth arrangement, starting from one of the first to thirdarrangements, the identification unit may further identify apredetermined observed range including an observed position within thedisplay region to which the line of sight of the user is directed, theobservation condition information may include at least one of a numberof times the line of sight of the user directed to the display regionmoves per unit time and a time for which the user views the displayregion within a unit time, the controlled region may be a portion of thedisplay region that is other than the predetermined observed range, andthe predetermined requirement may be the observation conditioninformation having a value equal to or smaller than a predeterminedthreshold.

In the fifth arrangement, the condition of the user viewing the displayregion may be identified based on at least one of the number of timesthe line of sight directed to the display region moves per unit time andthe time for which the line of sight is directed to the display regionwithin a unit time. Further, when the observation condition informationhas a value that is equal to or smaller than a predetermined threshold,writing of image signals in the portions of the display region that areother than the observed range for the user is halted for a predeterminedframe period. Thus, an image signal is written in the observed rangethat the user is viewing for each frame, and thus power consumptionencountered while an image is displayed will be reduced withoutdecreasing the visibility of images in the observed range or decreasingconvenience.

Starting from the fourth or fifth arrangement, a sixth arrangement mayfurther include: a backlight configured to illuminate the display unitwith light; and a backlight control unit configured to reduce aluminance of the backlight when the observation condition informationhas a value that is equal to or smaller than the predeterminedthreshold.

In the sixth arrangement, the luminance of the backlight is reduced whenthe observation condition information about the user has a value that isequal to or smaller than the predetermined threshold, thereby furtherreducing power consumption encountered while an image is displayed.

In a seventh arrangement, starting from the first arrangement, theobservation condition information may include an observed position inthe display region to which the line of sight of the user is directed,and the predetermined requirement may be a movement of the observedposition within the display region matching a predetermined movementpattern.

In the seventh arrangement, when a movement of the observed position ofthe user matches a predetermined movement pattern, writing of imagesignals in the controlled region is halted for a predetermined frameperiod. A movement of the observed position of the user reflects thecondition of the user viewing the display region. This will enablecontrolling display in a manner more suitable for the condition of theuser viewing the display region.

In an eighth arrangement, starting from one of the first to seventharrangements, the display unit may include an active-matrix substrate,the active-matrix substrate including: gate lines and source linesdisposed to cross the gate lines; pixel electrodes each provided for apixel defined by one of the gate lines and one of the source lines; andthin-film transistors each having a semiconductor layer provided aboveone of the gate lines, a gate terminal connected with that gate line, asource terminal connected with one of the source lines, and a drainterminal connected with one of the pixel electrodes, the source terminaland the drain terminal being located above the semiconductor layer andspaced apart from each other.

In a ninth arrangement, starting from the eight arrangement, thesemiconductor layer may contain an oxide semiconductor.

In a tenth arrangement, starting from the ninth arrangement, the oxidesemiconductor may contain indium, gallium, zinc and oxygen.

In an eleventh arrangement, starting from the tenth arrangement, theoxide semiconductor may be crystalline.

Now, embodiments of the present invention will be described in detailwith reference to the drawings. The same or corresponding components inthe drawings are labeled with the same characters and their descriptionwill not be repeated.

<First Embodiment>

(Construction)

FIG. 1 is a schematic block diagram of a display device in the presentembodiment. The display device 1 includes a control unit 11, a displaycontrol unit 12, a display unit 13, and a backlight 14. The displaydevice 1 is electrically connected with an image-capturing unit 2 thatis externally provided. These components will be described in detailbelow.

The image-capturing unit 2 may include an electronic camera, forexample. The electronic camera is located at a position on the displayscreen of the display device 1 that may be viewed by a user, and ismounted on the display device 1 so as to picture the face of the user.The image-capturing unit 2 is controlled by the control unit 11,discussed below, and provides image signals representing an imageobtained by picturing the face of the user (hereinafter referred to asanalysis image signals) to the control unit 11.

The control unit 11 includes an analyzing unit 111, an identificationunit 112, and a signal input unit 113. The control unit 11 includes acentral processing unit (CPU), not shown, and memories (i.e. read-onlymemory (ROM) and random-access memory (RAM)). The control unit 11performs the functions of the analyzing unit 111, identification unit112 and signal input unit 113 as the CPU executes a control programstored in the ROM. These components will be described below.

The analyzing unit 111 causes the image-capturing unit 2 to captureimages at regular intervals to acquire analysis image signals from theimage-capturing unit 2. The analyzing unit 111 analyzes the analysisimage signals to detect a line of sight of the user. More specifically,the analyzing unit 111 detects a face region of the user in an imagerepresented by the analysis image signals based on a predeterminedpattern image. The pattern image predefines the positions of variousparts of the face (i.e. eyes, nose and mouth) and color information(i.e. luminance and chroma), for example. The analyzing unit 111pattern-matches a pattern image with the image represented by theanalysis image signals to detect the face region and the positions ofthe eyes (i.e. eye coordinates) of the user in the image. Further, theanalyzing unit 111 identifies the position of the center of an eye ball(i.e. reference coordinates) in each of the eye portions based on thecurvature of the eye ball, and extracts a pupil portion from theportions of the image that correspond to the eye to detect the positionof the center of its pupil (i.e. pupil coordinates). The analyzing unit111 detects the direction running from the eye ball centers (i.e.reference coordinates) to the pupil centers (i.e. pupil coordinates) asa sight line vector. The analyzing unit 111 provides sight lineinformation indicating the positions of the eyes of the user (i.e. eyecoordinates) with respect to the display screen and the sight linevector for a predetermined time period to the identification unit 112.

Based on the sight line information from the analyzing unit 111, theidentification unit 112 calculates the number of times that the line ofsight of the user is directed to the display screen per unit time (i.e.number of times a movement occurs), and the average time for which theline of sight of the user is directed to the display screen for a unittime (hereinafter referred to as average stay time) to provideobservation condition information indicating the condition of the userviewing the display region.

More specifically, to determine the number of times that a movementoccurs per unit time, the identification unit 112 counts the number oftimes the line of sight moves from outside the display screen to withinthe display screen per unit time based on the sight line informationprovided by the analyzing unit 111 in regular intervals. It maydetermine whether the line of sight is directed to the display screen inthe following manner.

For example, the identification unit 112 determines that the line ofsight is directed to the display screen when the positions of the eyes(i.e. eye coordinates) contained in the sight line information are thosecorresponding to the eyes viewing the display image and the direction ofthe sight line vector is directed to the display screen. It should benoted that the identification unit 112 determines that the line of sightis directed to outside the display screen even when the positions of theeyes (i.e. eye coordinates) are those corresponding to the eyes viewingthe display screen if the direction of the sight line vector is notdirected to the display screen or the positions of the eyes (i.e. eyecoordinates) are not those corresponding to the eyes viewing the displayscreen.

In these cases, for example, the analyzing unit 111 may determine eyecoordinates (i.e. reference eye coordinates) from analysis image signalsobtained by capturing an image when the user is actually viewing thedisplay screen, and these coordinates may be stored in memory. Theidentification unit 112 may determine whether the eye coordinatescontained in the sight line information indicate the positionscorresponding to the eyes viewing the display screen with respect to thereference eye coordinates.

The identification unit 112 further determines the time from the pointat which the line of sight moves into the display screen until it movesoutside the display screen (hereinafter referred to as stay time) basedon analysis image signals. Then, the identification unit 112 calculatesthe average of stay times, each for a unit time, as an average staytime.

The signal input unit 113 acquires image signals for display suppliedfrom outside (hereinafter referred to as display image signals) andprovides them to the display control unit 12 and display unit 13.

The display unit 13 will be described below. The display unit 13includes a display panel driver 130 and a display panel 131. As shown inFIG. 2, the display panel 131 includes an active-matrix substrate 131 athat passes light, a counter-substrate 131 b, and a liquid crystal layer(not shown) sandwiched therebetween. Although not shown in FIG. 2, acommon electrode (not shown) and color filters (not shown) are providedon the side of the counter-substrate 131 b that is adjacent to theliquid crystal layer (not shown). A polarizer (not shown) is provided onthe front side (positive along the Z axis) of the counter-substrate 131b, and another one is provided on the back side (negative along the Zaxis) of the active-matrix substrate 131 a.

A backlight 14 is located adjacent the back side (negative along the Zaxis) of the active-matrix substrate 131 a. Light emitted from thebacklight 14 passes through the display panel 131 and is emitted throughthe front side (positive along the Z axis) of the display panel 131,that is, the side of the display screen that is viewed.

The active-matrix substrate 131 a and components for driving theactive-matrix substrate 131 a will be described below. FIG. 3 is aschematic view of the active-matrix substrate 131 a and variouscomponents for driving the active-matrix substrate 131 a.

The active-matrix substrate 131 a includes a plurality of gate lines 31and a plurality of source lines 32 disposed to cross the gate lines 31.The display screen is composed of pixels formed by these gate lines 31and source lines 32.

The construction of a pixel will be described below. FIG. 4A is anexample equivalent circuit of one pixel. As shown in FIG. 4A, the pixelPIX includes a thin-film transistor (TFT) 30 located near theintersection of a gate line 31: G(n) and source line 32, and a pixelelectrode 33 connected with the TFT 30. The TFT 30 includes a gateterminal 1312 (see FIG. 4B) connected with the gate line 31, a sourceterminal 1316 (see FIG. 4B) connected with the source line 32, and adrain terminal 1315 (see FIG. 4B) connected with the pixel electrode 33.The pixel PIX includes a liquid crystal capacitor LC formed by the pixelelectrode 33, a common electrode (COM) provided on the counter-substrate131 b and the liquid crystal layer (not shown).

FIG. 4B is a schematic cross-sectional view of the pixel PIX. Theactive-matrix substrate 13 includes a glass substrate 1311 and a gateline layer 1312 provided above the glass substrate. As the gate linelayer 1312 is formed, the gate line 31 and the gate terminal of the TFT30 are integrally formed. A gate insulating film 1313 is provided on thegate line layer 1312. A semiconductor layer 1314 is provided above thegate line layer 1312, where the gate insulating film 1313 is locatedtherebetween. A source line layer 1316 and the drain terminal 1315 ofthe TFT 30 are provided above the gate line layer 1312, where the gateinsulating film 1313 is located therebetween, the source line layer anddrain terminal located on the top of the semiconductor layer 1314 andspaced apart from each other. Thus, a channel region C is provided abovethe semiconductor layer 1314. As the source line layer 1316 is formed,the source line 32 and the source terminal of the TFT 30 are integrallyformed. A protection layer 1317 formed of an insulating film such asSiO2 is provided on the source line layer 1316, channel region C anddrain terminal 1315. Above the protection layer 1317 is provided a pixelelectrode 33 connected with the drain terminal 1315 via a contact hole Hin the protection layer 1317.

In the present embodiment, the semiconductor layer 1314 may be, forexample, an indium (In)-gallium (ga)-zinc (Zn)-oxide (O)-based oxidesemiconductor layer. The semiconductor layer 1314 contains anIn—Ga—Zn—O-based semiconductor. The In—Ga—Zn—O-based semiconductor is aternary oxide of In, Ga and Zn, where the ratio of In, Ga and Zn (i.e.composition ratio) is not limited to any particular value. For example,In:Ga:Zn=2:2:1, In:Ga:Zn=1:1:1, In:Ga:Zn=1:1:2 may be used. Thesemiconductor layer 1314 in the present embodiment uses anIn—Ga—Zn—O-based semiconductor that contains In, Ga and Zn in a ratio of1:1:2. The TFT 30 having a semiconductor layer 1314 containing anIn—Ga—Zn—O-based semiconductor has a mobility that is at least about 20times as large as a TFT using a-Si and a leak current that is smallerthan about one hundredth of that of a TFT using a-Si, and thus can besuitably used as a TFT for driving a pixel. Using in the display device1 TFTs 30 having a semiconductor layer 1314 containing anIn—Ga—Zn—O-based semiconductor significantly reduces the powerconsumption of the display device 1.

The In—Ga—Zn—O-based semiconductor may be amorphous, or may contain acrystalline substance and thus be crystalline. One preferablecrystalline In—Ga—Zn—O-based semiconductor is a crystallineIn—Ga—Zn—O-based semiconductor with a c axis that is oriented to begenerally perpendicular to the layer plane. A crystalline structure ofsuch an In—Ga—Zn—O-based semiconductor is disclosed in JP 2012-134475 A,for example. JP 2012-134475 A is incorporated by reference herein in itsentirety.

The semiconductor layer 1314 may include, instead of an In—Ga—Zn—O-basedsemiconductor, other oxide semiconductors. More specifically, thesemiconductor layer 1314 may include, for example, a Zn—O-basedsemiconductor (ZnO), an In—Zn—O-based semiconductor (IZO (registeredtrademark)), a Zn-titanium (Ti)—O-based semiconductor (ZTO), a cadmium(Cd)-germanium (Ge)—O-based semiconductor, a Cd-lead (Pb)—O-basedsemiconductor, cadmium oxide (CdO)-magnesium (Mg)—Zn—O-basedsemiconductor, an In-tin (Sn)—Zn—O-based semiconductor (for example, In2O3-SnO2-ZnO), or In-gallium (Ga)—Sn—O-based semiconductor.

Returning to FIG. 3, based on a clock signal and common electrode drivesignal supplied by the display panel drive control unit 121, describedbelow, the display panel driver 130 applies a predetermined commonelectrode voltage to the common electrode (not shown) provided on thecounter-substrate 131 b. The display panel driver 130 further includes asource driver 130 a and a gate driver 130 b. The gate driver 130 b iselectrically connected with the gate lines 31 and the source driver 130a is electrically connected with the source lines 32.

The gate driver 130 b receives a drive control signal including a clocksignal, a start pulse signal and a stop control signal from the displaypanel drive control unit 121, described below. Based on the drivecontrol signal, the gate driver 130 b successively provides an H-levelvoltage signal for selecting a gate line 31 (hereinafter referred to asselect voltage signal) or an L-level voltage signal for making a gateline 31 non-selected (hereinafter referred to as non-select voltagesignal) to the gate lines 31. A select voltage signal being supplied toa gate line 31 will also be hereinafter referred to as driving of thegate line 31.

The source driver 130 a is electrically connected with the signal inputunit 113. The source driver 130 a generates a data signal that isobtained by converting a gray-scale value for each color contained in adisplay image signal supplied by the signal input unit 113 to a voltagevalue. The source driver 130 a receives a drive control signal includinga clock signal, a start pulse signal and a stop control signal from thedisplay panel drive control unit 121, described below. The drive controlsignal for the gate driver 130 b and the drive control signal for thesource driver 130 a are synchronized. Based on the associated drivecontrol signal, the source driver 130 a provides, to the source lines32, data signals to be written to pixels in the timing in which gatelines 31 are scanned.

Returning to FIG. 1, the backlight 14 includes a plurality oflight-emitting diodes (LEDs). The backlight 14 is electrically connectedwith a backlight drive control unit 122, described below. The backlight14 turns LEDs on at a luminance as indicated by backlight drive controlunit 122.

The display control unit 12 includes a display panel drive control unit121 and a backlight drive control unit 122. The display panel drivecontrol unit 121 is electrically connected with the display panel driver130. The display panel drive control unit 121 controls the display paneldriver 130 to display an image on the display panel 131 according to adisplay control pattern corresponding to the observation conditioninformation identified by the identification unit 112. The backlightdrive control unit 122 controls the luminance of the backlight 14according to a display control pattern corresponding to the observationcondition information identified by the identification unit 112.

Observation condition information corresponding to a display controlpattern will be described. FIG. 5 illustrates the correspondence betweenthe display control pattern in the present embodiment and theobservation condition information (i.e. number of times the line ofsight moves per unit time (M) and average stay time (T)). In thisexample, the display control pattern may be one of Patterns A to D. Asshown in FIG. 5, Pattern A is performed when the observation conditioninformation meets the requirement 1≦M≦3 and 5<T≦60 (seconds). Pattern Bis performed when the observation condition information meets therequirement 1≦M≦3 and 0≦T≦30 (seconds). Pattern C is performed when theobservation condition information meets the requirement 1≦M≦2 and 0≦T≦10(seconds). Pattern D is performed when the observation conditioninformation meets the requirement M=1 and 0≦T≦5 (seconds). In FIG. 5,the smaller the number of times the line of sight moves and the averagestay time, the less likely the user is to view the display screen; thelarger the number of times the line of sight moves and the average staytime, the more likely the user is to view the display screen.

When the observation condition information identified by theidentification unit 112 meets one of the requirements shown in FIG. 5,the display panel drive control unit 121 and backlight drive controlunit 122 performs display controls based on the display control patterncorresponding to that requirement. When the observation conditioninformation identified by the identification unit 112 does not meet anyof the requirements shown in FIG. 5, that is, when the number of timesthe line of sight moves per unit time (M) is 4 or larger or the averagestay time of the line of sight (T) is larger than 60 seconds, thedisplay panel drive control unit 121 and backlight drive control unit122 performs a normal control. Controls by the display panel drivecontrol unit 121 and backlight drive control unit 122 will be describedbelow.

The display panel drive control unit 121 provides a common electrodedrive signal and a drive control signal to the display panel driver 130.When the observation condition information meets one of the requirementsshown in FIG. 5, the display panel drive control unit 121 provides astop control signal to the source driver 130 a and gate driver 130 baccording to the display control pattern corresponding to thatrequirement to perform display controls to halt, for a predeterminedtime period, writing of data signals in part of the display screen or inthe entire display screen. In the present embodiment, for example, whena data signal of a display image signal is to be written to the displaypanel 131 at 60 Hz, display controls are performed at 1 Hz. The normalcontrol and the display controls based on the display control patterns,i.e. Patterns A to D, will be described below.

The normal control will be discussed first. FIG. 6 is a timing chartillustrating how data signals are written when the normal control isperformed. FIG. 6 illustrates an implementation where gate lines 31:G(1) to G(n) are provided on the active-matrix substrate 131 a.

The display panel drive control unit 121 provides the clock signal andcommon electrode drive signal to the display panel driver 130, and usesthe display panel driver 130 to apply a predetermined common electrodevoltage to the common electrode (not shown). The backlight drive controlunit 122 turns the backlight 14 on at a predetermined luminance. Foreach of the first to 60th frames, the display panel drive control unit121 provides the clock signal, start pulse signal and L-level stopcontrol signal as drive control signals to the gate driver 130 b andsource driver 130 a. As such, as shown in FIG. 6, the gate lines 31:G(1) to G(n) successively receive the H-level select voltage signal fromthe gate driver 130 b such that all the gate lines 31 are successivelydriven. Then, data signals are provided to the source lines 32 from thesource driver 130 a in synchronization with the timing in which the gatelines 31: G(1) to G(n) are driven.

Thus, the liquid crystal capacitance LC of each pixel PIX changesdepending on the voltage of a data signal applied via the TFT 30 suchthat data signals are written in the entire display region for eachframe. Thus, according to the normal control, an image corresponding toa data signal is displayed on the display screen for each of the firstto 60th frames.

Writing of data signals under the display control based on Pattern Awill be described below. The display control based on Pattern A halts,for a predetermined time period, writing of data signals in a displayregion for a static image contained in an image represented by displayimage signals (hereinafter referred to as static image region), andturns the backlight 14 on at the predetermined luminance, equal to thatfor the normal control.

FIG. 7A is a timing chart illustrating how data signals are written whenthe display control for Pattern A is performed. FIG. 7B is a schematicview of an example static image region on the active-matrix substrate131 a. In the implementation of FIG. 7B, the static image region isdefined by a rectangle R (hereinafter referred to as static image regionR), where parts of gate lines 31: G(1) to G(m) are located in the staticimage region R.

As discussed above, in the present embodiment, the display panel drivecontrol unit 121 writes data signals to the display panel 131 at 60 Hz,and performs the display control based on Pattern A at 1 Hz. As is thecase with the normal control shown in FIG. 6, for the first frame, thedisplay panel drive control unit 121 successively drives all the gatelines 31: G(1) to G(n), and provides data signals to the source lines 32in synchronization with the timing in which the gate lines 31 aredriven. Thus, for the first frame, data signals are written in theentire display region.

For each of the second to 60th frames, the display panel drive controlunit 121 provides an H-level stop control signal to the gate driver 130b and source driver 130 a in the timing in which the gate lines 31: G(1)to G(m) partially located in the static image region R are scanned, andprovides an L-level stop control signal in the timing in which the othergate lines 31 are scanned.

For each of the second to 60th frames, the gate driver 130 b provides anon-select voltage signal to the gate lines 31: G(1) to G(m) in thetiming in which the gate lines 31: G(1) to G(m) are scanned to which anH-level stop control signal is provided from the display panel drivecontrol unit 121, and provides a select voltage signal in the timing inwhich the other gate lines 31 are scanned to which an L-level stopcontrol signal is provided from the display panel drive control unit121. The source driver 130 a provides data signals to the source lines32 in the timing in which those gate lines 31 are scanned that are otherthan the gate lines 31: G(1) to G(m) to which an L-level stop controlsignal is provided from the display panel drive control unit 121.

Thus, as shown in FIG. 7A, for each of the second and following frames,the gate lines 31: G(1) to G(m) are not driven, and the gate lines 31that are other than the gate lines 31: G(1) to G(m) are successivelydriven and data signals are provided to the source lines 32 in thetiming in which the other gate lines 31 are driven. As such, no datasignal is written in the static image region R for the second to 60thframes, while data signals are written in the portion of the displayregion that is other than the static image region R for each frame.

Since a static image has less movement than a moving image, visibilityis unlikely to decrease even if writing of data signals for the staticimage region R is halted for the second to 60th frames. Further, asshown in FIG. 5, the observation condition information corresponding toPattern A indicates that the user is not watching the display screencontinuously for an extended period of time, but sometimes glances atthe display screen; since an image is displayed on the display screeneven when the display control based on Pattern A is performed, the useris less likely to notice something odd than in implementations where noimage is displayed when the user views the display screen, andconvenience is not impaired, either. Further, as writing of data signalsfor the static image region R is halted for a predetermined frameperiod, power consumption encountered while an image is displayed on thedisplay panel 131 is smaller than when the normal control is performed.

The static image region R may be identified in the following manner: foreach frame of a display image signal supplied from the signal input unit113, the display panel drive control unit 121 may determine thedifference between this frame and the preceding frame, and identify theportion of the display region for which no difference was detected asthe static image region R. Further, for each frame of a display imagesignal, the signal input unit 113 determines the difference between thisframe and the preceding frame. The signal input unit 113 may provide, tothe display panel drive control unit 121, static image informationindicating a coordinate range corresponding to a static image region forwhich a detected difference is below a threshold, or provide, to thedisplay panel drive control unit 121, non-static image informationindicating a coordinate range corresponding to a non-static image regionfor which a detected difference is not smaller than a threshold. Whenstatic image information is provided by the signal input unit 113, thedisplay panel drive control unit 121 performs the display control basedon Pattern A for the static image region indicated by the static imageinformation. When non-static image information is provided by the signalinput unit 113, the display panel drive control unit 121 designates theportion of the display region that is other than the non-static imageregion indicated by the non-static image information as a static imageregion, and performs the display control based on Pattern A.

The display control based on Pattern B will now be described. Thedisplay control based on Pattern B halts writing of data signals for apredetermined time in the entire display region, and turns the backlight14 on at a predetermined luminance.

As is the case with the normal control shown in FIG. 6, for the firstframe, the display panel drive control unit 121 successively drives allthe gate lines 31: G(1) to G(n), and provides data signals to the sourcelines 32 in the timing in which the gate lines 31: G(1) to G(n) aredriven. Thus, for the first frame, data signals are written in theentire display region.

For the second to 60th frames, the display panel drive control unit 121provides an H-level stop control signal to the gate driver 130 b andsource driver 130 a to stop providing of start pulse signals. Thus, asshown in FIG. 8, for the second to 60th frames, scanning of all the gatelines 31: G(1) to G(n) is halted, and no data signal is supplied to thesource lines 32. Thus, according to Pattern B, the image represented bythe data signals written for the first frame remains displayed for thesecond to 60th frames.

Since a moving image has more movement than a static image, thevisibility of images displayed on the display screen decreases aswriting of data signals is halted for the second to 60th frames.However, as shown in FIG. 5, the observation condition informationcorresponding to Pattern B has a shorter average stay time during whichthe user views the display screen than that for Pattern A. Further, animage remains displayed on the display screen even when writing of datasignals for the entire display image is halted for a predetermined frameperiod. Thus, the user is less likely to notice something odd than inimplementations where no image is displayed when the user is viewing thedisplay screen, and convenience is not impaired, either. Further, powerconsumption encountered while an image is displayed on the display panel131 is smaller than when writing of data signals for only a part of thedisplay region is halted, as is the case with Pattern A.

The display control based on Pattern C will now be described. Thedisplay control based on Pattern C performs the display control based onPattern B at 0.5 Hz. As is the case with Pattern B, for the first frame,the display panel drive control unit 121 successively drives all thegate lines 31: G(1) to G(n) to provide data signals to the source lines32. Thus, for the first frame, data signals are written in the entiredisplay region. Then, for each of the second to 120th frames, thedisplay panel drive control unit 121 provides an H-level stop controlsignal to the gate driver 130 b and source driver 130 a to stopproviding of start pulse signals. Thus, as shown in FIG. 9, for thesecond to 120th frames, scanning of all the gate lines 31: G(1) to G(n)is halted and no data signal is provided to the source lines 32. Thus,according to Pattern C, the image represented by the data signalswritten for the first frame remains displayed for the second to 120thframes.

According to Pattern B, data signals are written in the entire displayscreen once per 60 frames, while according to Pattern C, data signalsare written in the entire display screen once per 120 frames. As such,the visibility of images is smaller than that for Pattern B. However, asshown in FIG. 5, the observation condition information corresponding toPattern C has a smaller number of times the user moves his line of sightto the display screen and a shorter average stay time than those forPattern B. Further, an image is also displayed on the display screenaccording to Pattern C, the user is less likely to notice something oddthan when no image is displayed on the display screen when the user isviewing the display screen, and convenience is not impaired, either.Furthermore, Pattern C has a longer time during which writing of datasignals is halted than Pattern B such that power consumption encounteredwhile an image is displayed is smaller than that for Pattern B.

The display control based on Pattern D will be described below. Startingfrom the display control based on Pattern C, the display control basedon Pattern D turns the backlight 14 on at a luminance that is smallerthan the predetermined luminance. That is, according to Pattern D, thedisplay panel drive control unit 121 writes data signals in the entiredisplay screen once for 120 frames, and the backlight drive control unit122 turns the backlight 14 on at the predetermined luminance minus acertain amount.

As the luminance of the backlight 14 is smaller than that for Pattern C,the visibility of the display screen decreases. However, as shown inFIG. 5, the observation condition information of Pattern D indicatesthat the user is hardly viewing the display screen. An image isdisplayed on the display screen even when the display control based onPattern D is performed, and thus the user is less likely to noticesomething odd when viewing the display screen than in implementationswhere no image is displayed on the display screen, and convenience isnot impaired, either. Furthermore, according to Pattern D, the backlight14 is turned on at a smaller luminance than according to Pattern C suchthat power consumption is smaller than according to Pattern C.

In the present embodiment, an H-level stop control signal is provided tothe source driver 130 a and gate driver 130 b to perform idled drivingwhere the operations of the driving circuits, i.e. the source driver 130a and gate driver 130 b for driving the display panel 131 are halted forthe second to 60th frames (i.e. idled period); alternatively, an H-levelstop control signal may be provided to one of the source driver 130 aand gate driver 130 b to halt the operation of one driving circuit forthe idled period.

In the first embodiment described above, the display device 1 identifiesobservation condition information indicating the condition of the userviewing the display screen based on results of analyzing analysis imagesignals obtained by picturing the user. Then, the display device 1writes display image signals to the display panel 131 for each frameaccording to the display control pattern corresponding to theobservation condition information. That is, display image signals arewritten in a manner that depends on the condition of the user viewingthe display screen. Thus, even when the user sometimes glances at thedisplay screen, power consumption encountered while an image isdisplayed is reduced without decreasing the visibility of the displayscreen or convenience.

<Second Embodiment>

The present embodiment describes an implementation where writing ofimage signals is halted according to display control patterns that aredifferent from those of the first embodiment. The differences from thefirst embodiment will be described below. FIG. 10 illustrates thecorrespondence between the observation condition information and displaycontrol pattern in the present embodiment. In FIG. 10, Patterns A to Care the same as in the first embodiment. The present embodiment isdifferent from the first embodiment in that Pattern D is not provided asa display control pattern and Pattern E is additionally provided inaddition to Patterns A to C.

In this implementation, Pattern E is performed when the observationcondition information meets the requirement 1≦M≦3 and 5<T≦60 (seconds).Pattern A of the present embodiment is performed when the observationcondition information meets the requirement 1≦M≦3 and 0≦T≦30 (seconds).Pattern B of the present embodiment is performed when the observationcondition information meets the requirement 1≦M≦2 and 0≦T≦10 (seconds).Pattern C of the present embodiment is performed when the observationcondition information meets the requirement M=1 and 0≦T≦5 (seconds).

The display control based on Pattern E halts writing of data signals fora predetermined frame period in the portions of the display region thatare other than a specified display region. That is, the display controlbased on Pattern E writes data signals in the specified display regionfor each frame, as is the case with the normal control, and writes datasignals in the other display region portions according to a displaycontrol pattern corresponding to the observation condition information.The specified display range is a viewed range within the display regionthat can be arbitrarily defined with respect to an observed position onthe display screen that the user is viewing.

Based on analysis results from the analyzing unit 111 as well as theobservation condition information, the identification unit 112identifies an observed position on the display screen to which the lineof sight of the user is directed. In the present embodiment, theidentification unit 112 identifies, for example, the sight line vectorwith the longest stay time of the line of sight for a unit time and thepositions of the eyes (i.e. eye coordinates) found when this sight linevector is obtained. Then, the identification unit 112 determines thecoordinates of the observed position by, for example, substituting theidentified eye coordinates and sight line vector into a predeterminedarithmetic expression that has eye coordinates and sight line vector asvariables and specifies a position on the display region. Theidentification unit 112 identifies a predetermined range with respect tothe coordinates of the observed position as an observed range. Thisobserved range may be defined by coordinates on a circumference with anarbitrary diameter with respect to the observed position, for example.The identification unit 112 provides the identified observed range andthe number of times the line of sight moves and the average stay time tothe display panel drive control unit 121.

When the display control pattern corresponding to the number of timesthe line of sight moves and the average stay time is Pattern E, thedisplay panel drive control unit 121 provides drive control signals tothe display panel driver 130 so as to successively drive the gate lines31 partially located within the observed range identified by theidentification unit 112 for each frame, and to halt scanning of theother gate lines 31 for the second to 60th frames.

For example, an example display control based on Pattern E will bedescribed where, on the active-matrix substrate 131 a shown in FIG. 11A,an observed range defined by a circle r (i.e. observed range r) isidentified by the identification unit 112, and the gate lines 31: G(i)to G(m) are partially located in the observed range r. As is the casewith the normal control shown in FIG. 6, for the first frame, thedisplay panel drive control unit 121 successively drives the gate lines31: G(1) to G(n) to provide data signals to the source lines 32.

For the second to 60th frames, the display panel drive control unit 121provides an L-level stop control signal to the gate driver 130 b andsource driver 130 a in the timing in which the gate lines 31: G(i) toG(k) partially located in the observed range r are scanned. Further, forthe second to 60th frames, the display panel drive control unit 121provides an H-level stop control signal in the timing in which the othergate lines 31 are scanned.

For each of the second to 60th frames, the gate driver 130 b provides aselect voltage signal to the gate lines 31: G(i) to G(k) in the timingin which the gate lines 31: G(i) to G(k) are scanned. Further, for eachof the second to 60th frames, the gate driver 130 b provides anon-select voltage signal to the other gate lines 31 in the timing inwhich the gate lines 31 that are other than the gate lines 31: G(i) toG(k) are scanned.

The source driver 130 a provides data signals to the source lines 32 inthe timing in which the gate lines 31: G(i) to G(k) are scanned. Then,the source driver 130 a halts providing of data signals to the sourcelines 32 in the timing in which the other gate lines 31 are scanned.Thus, as shown in FIG. 11B, for each of the second to 60th frames, datasignals are provided in the timing in which the gate lines 31: G(i) toG(k) are successively driven. Thus, data signals are written in theobserved range r for each frame, while data signals are written in theportions of the display region that are other than the observed range ronly for the first frame, and no data signal is written for the secondto 60th frames.

As shown in FIG. 10, Pattern E indicates that the user sometimes glancesat the display screen. Thus, the visibility of the portion of the imagethat the user views is maintained as data signals are written in theobserved range viewed by the user for each frame. Thus, even whenwriting of data signals in the portions of the display region that areother than the observed range viewed by the user is halted for apredetermined frame period, the user is unlikely to notice somethingodd, and convenience is not impaired, either. Further, power consumptionencountered while an image is displayed on the display screen is smallerthan in implementations where the normal control is performed.

While embodiments of the present invention have been described, theseembodiments are merely examples used to carry out the present invention.Thus, the present invention is not limited to these embodiments, and theembodiments can be varied as appropriate without departing from thespirit of the invention. Variations of the present invention will bedescribed below.

<Variations>

(1) In each of the first and second embodiments described above, theidentification unit 112 identifies a number of times the line of sightmoves per unit time (M) and an average stay time (T) as observationcondition information; alternatively, one of a number of times amovement occurs (M) and an average stay time (T) may be identified asobservation condition information. Further, the identification unit 112may identify, instead of an average stay time (T), the sum of stay timesof the line of sight within a unit time.

(2) In the first embodiment described above, the display control basedon Pattern D starts from the display control based on Pattern C andcontrols the backlight 14 to have the predetermined luminance minus acertain amount; alternatively, for example, it may start from thedisplay controls based on Patterns A, B and C and control the backlight14 to have the predetermined luminance minus an amount that increases asthe number of times a movement occurs or the average stay time decreasefor Patterns A, B and C.

More specifically, when the observation condition informationcorresponding to Pattern A in FIG. 5 is M=3 and 30<T≦60 (seconds), thebacklight drive control unit 122 controls the backlight 14 to have apredetermined luminance (hereinafter referred to as first luminance).For M=2 or 10<T≦30 (seconds), the backlight drive control unit 122controls the backlight 14 to have the first luminance minus a certainamount, i.e. a second luminance. Furthermore, for M=1 or 5<T≦10(seconds), the backlight drive control unit 122 controls the backlight14 to have the second luminance minus a certain amount, i.e. a thirdluminance.

In the present variation, the luminance of the backlight 14 may becontrolled such that the amount by which the luminance of the backlight14 is reduced is expressed as Patterns A<B<C. Furthermore, starting fromthe second embodiment described above, as is the case with the presentvariation, the controls based on Patterns A, B, C and E may be done and,in addition, the backlight 14 may be controlled to have thepredetermined luminance minus a certain amount.

(3) In each of the first and second embodiments described above, anumber of times the line of sight moves per unit time (M) and an averagestay time (T) are identified as observation condition information, anddata signals are written according to the display control patterncorresponding to the observation condition information; alternatively,the display device 1 may use the identification unit 112 to identify anobserved position on the display region viewed by the user asobservation condition information.

When the movement of the observed position matches a predeterminedmovement pattern, the display panel drive control unit 121 may haltwriting of data signals for a predetermined frame period according tothis movement pattern.

For example, when the user causes the display device 1 to display animage of a book and is reading it, the observed position in the displayregion to which the line of sight of the user is directed movesregularly, as indicated by the set of broken lines P in FIG. 12(a). Whenthe track of the observed position in the display region matches thetrack indicated by the broken lines P in FIG. 12(a), the display paneldrive control unit 121 may perform display controls according to thedisplay control pattern of Pattern B, discussed above.

Further, for example, when the user causes the display device 1 todisplay an image for a game and is doing operations for the game, theobserved position of the user randomly moves, as shown by the set ofbroken lines P in FIG. 12(b). When the track of the observed position inthe display region matches the track indicated by the broken lines P inFIG. 12(b), the display panel drive control unit 121 may perform thenormal control.

The identification unit 112 may identify, as observation conditioninformation, not only an observed position on the display region butalso a speed of movement of the observed position for a unit time or arange of movement of the observed position, for example. In such cases,the display panel drive control unit 121 may determine that operationsfor a game are being done when, for example, the movement of theobserved position matches the movement pattern of FIG. 12(b) and thespeed of movement of the observed position is equal to or larger than apredetermined threshold and the range of movement is not smaller than apredetermined range. Further, the display panel drive control unit 121may acquire from the control unit 11 or an external device a type ofapplication for an image being displayed on the display device 1 andperform display controls as described above according to the type ofapplication and the observation condition information. This arrangementwill enable determining the use condition of the user in a more reliablemanner than in implementations where the use condition of the user isdetermined only based on the observation condition information, therebyenabling appropriate display controls depending on the use condition.

(4) In the first and second embodiments described above, idled drivingis performed where driving of some or all the gate lines 31 in thedisplay region and supplying of data signals to the source lines 32 arehalted for a predetermined frame period. In idled driving, driving ofsome or all the gate lines 31 in the display region may be halted for apredetermined frame period, or supplying of data signals to the sourcelines 32 may be halted for a predetermined frame period. Further, inidled driving, supplying of control signals such as a clock signal tothe driving circuits (i.e. source driver 130 a and gate driver 130 b)whose operation is to be halted may be halted. In short, it is onlyrequired that writing of data signals to a part of the display region orthe entire display region be halted for a predetermined frame period.

INDUSTRIAL APPLICABILITY

The present invention is industrially useful as a display device for atelevision set or personal computer.

The invention claimed is:
 1. A display device comprising: a display unithaving a display region in which an image signal is written; a detectionunit configured to analyze an image obtained by picturing a user anddetect a line of sight of the user with respect to the display region;an identification unit configured to identify observation conditioninformation indicating a condition of the user viewing the displayregion based on the line of sight detected by the detection unit; and adisplay control unit configured to write the image signal in the displayregion for each frame, wherein the display control unit halts, for apredetermined frame period, writing of the image signal in a controlledregion when the observation condition information identified by theidentification unit meets a predetermined requirement, the controlledregion being at least a part of the display region; wherein theidentification unit further identifies a predetermined observed rangeincluding an observed position within the display region to which theline of sight of the user is directed, the observation conditioninformation includes at least one of a number of times the line of sightof the user directed to the display region moves per unit time and atime for which the user views the display region within a unit time, thecontrolled region is a portion of the display region that is other thanthe predetermined observed range, and the predetermined requirement isthe observation condition information having a value equal to or smallerthan a predetermined threshold.
 2. The display device according to claim1, wherein the display control unit changes a length of thepredetermined frame period depending on the observation conditioninformation.
 3. The display device according to claim 1, wherein thecontrolled region is a static image region of the display region inwhich a static image contained in an image represented by the imagesignal is displayed.
 4. The display device according to, claim 1,wherein: the observation condition information includes at least one ofa number of times the line of sight of the user directed to the displayregion moves per unit time and a time for which the user views thedisplay region within a unit time, and the predetermined requirement isthe observation condition information having a value equal to or smallerthan a predetermined threshold.
 5. The display device according to claim4, further comprising: a backlight configured to illuminate the displayunit with light; and a backlight control unit configured to reduce aluminance of the backlight when the observation condition informationhas a value that is equal to or smaller than the predeterminedthreshold.
 6. The display device according to claim 1, wherein: theobservation condition information includes an observed position in thedisplay region to which the line of sight of the user is directed, andthe predetermined requirement is a movement of the observed positionwithin the display region matching a predetermined movement pattern. 7.The display device according to, claim 1, wherein: the display unitincludes an active-matrix substrate, the active-matrix substrateincluding: gate lines and source lines disposed to cross the gate lines;pixel electrodes each provided for a pixel defined by one of the gatelines and one of the source lines; and thin-film transistors each havinga semiconductor layer provided above one of the gate lines, a gateterminal connected with that gate line, a source terminal connected withone of the source lines, and a drain terminal connected with one of thepixel electrodes, the source terminal and the drain terminal beinglocated above the semiconductor layer and spaced apart from each other.8. The display device according to claim 7, wherein the semiconductorlayer contains an oxide semiconductor.
 9. The display device accordingto claim 8, wherein the oxide semiconductor contains indium, gallium,zinc and oxygen.
 10. The display device according to claim 9, whereinthe oxide semiconductor is crystalline.